Most animals require dental attention from time to time and many appliances have been developed to facilitate dental work on animals, and in particular on horses. The teeth of horses often develop spikes or sharp edges and these must be removed in order to prevent damage to the inside walls of the horse's mouth or to its tongue. When a horse must have a bit in its mouth there will be some damage to the teeth that must be kept in check. Typically a veterinarian will use a file to file away the spikes or sharp edges and that can be an awkward and tiring procedure. The veterinarian must keep the horses's mouth open and he must manoeuver the file within the mouth to perform his filing operation. Very often the spike or sharp edge is near the back of the horse's mouth and it can be very difficult to reach into the depths of the mouth and still do an effective job without damaging the interior walls (mucosa) of the mouth.
There is a need for a dental appliance or tool that will make the filing or grinding job easier and safer. One such device is described in U.S Pat. No. 4,722,685 of Feb. 2, 1988, issued to Juan M. de Estrada. That patent teaches an elongated hollow tube that carries a drive shaft driven by an electric motor. At one end the shaft mounts a dental bur that is rotated by the drive shaft and which is used to grind away the spikes or sharp edges on the horse's teeth. The dental bur is cylindrical, with a cylindrical grinding surface. The tube acts as a handle for the operator which means that it must be held like a wand as it is inserted into the horse's mouth. This is an awkward manoeuver for the operator and can be very tiring as he tries to work on upper and lower teeth and in particular the teeth at the back of the horse's mouth. Furthermore, the cylindrical nature of the dental bur means that it is difficult to effectively grind sharp spikes that are narrower than the diameter of the bur and that it is difficult to grind a smooth flat surface on any particular tooth in view of the cylindrical nature of the bur. The rotary bur tends to "jump" sideways while the operator is attempting to grind the teeth that are in a longitudinal row. There is additional difficulty in maneuvering the tube for grinding upper and lower teeth in the horse's mouth. Furthermore, the motor operates at a constant speed and does not allow flexibility for the operator when faster or slower speeds are needed for different areas of the mouth or for different tooth conditions. Thus, while the tool of this patent has some meritorious features, it also has drawbacks which render it somewhat ineffective for fine grinding of a horse's teeth.